Bags made of plastic film such as thin polyethylene film have been used in various sizes. Small bags are used in the packaging of sandwiches and the like; larger bags are used for shopping bags and even larger bags are used for containing trash. The present invention is particularly related to a draw tape bag having a microencapsulated adhesive in the draw tape hem for preventing the bag from inadvertently coming open.
A particularly advantageous closure for such bags includes a draw band or tape constructed from the same polyethylene material. Draw tape bags of this type have been known for several years and are described in various patents such as, for example, U.S. Pat. No. 3,029,853-Piazze. Bags of this type are formed by two pliable plastic sheets joined to one another on three sides and open at a fourth. The tubular hem is provided at the open end and of each sheet and contains a pliable thermoplastic strip. A hole or opening at the center of each hem exposes the strip in the hems allowing them to be pulled through the opening and used as a handle while simultaneously closing the open mouth of the bag. A similar type bag is disclosed in U.S. Pat. No. 4,624,654-Boyd et al. Draw tapes in the bags disclosed in these patents are at the same level in both hems of the bag. Draw tape bags using two tapes at different parallel levels in the bags are disclosed in U.S. Pat. No. 3,547,341-Kirkpatrick and Pat. No. 3,738,568-Ruda. In both of these patents the openings for pulling the draw tapes are at the opposite ends of the bag.
The present invention is also applicable to bags of the types disclosed in Broderick et al application Ser. No. 100,648, filed Sept. 24, 1987 entitled "Dual Draw Tape Bag and Method of Manufacture", Broderick et al application Ser. No. 100,649, filed Sept. 24, 1987 entitled "Draw Tape Bag with Two Single Tapes" and Broderick et al application Ser. No. 115,308, filed Nov. 2, 1987, entitled "Draw Tape Bag with Two Single Wraparound Draw Tapes and Method of Manufacture", all assigned to the assignee of the present application and incorporated herein by reference thereto.